[This is usually used in the phrase “rarer than hen’s teeth” or, when something is in very short supply, “scarcer than hen’s teeth.” Even though hens actually have no teeth (hence the expression), the phrase nevertheless typically refers to something that is very rare, but not impossible to occur.] As it turned out, the twins were neither fraternal nor identical. They fell into a third rare category known as semi-identical or sesquizygotic twins. The pair share 100 percent of their mother’s DNA, but only overlap in a portion of their father’s DNA. “Broadly they are about three-fourths identical,” said Dr. Fisk, adding that “it’s almost as rare as hen’s teeth.” (Heather Murphy, “Congratulations. It’s Twins. The Doctor is Perplexed,” The New York Times, 3/8/2019.)
hen’s teeth may also be used as a synonym for anything which is very unusual, uncommon, scarce, unique or infrequent.
Leave a Reply